It is common for the electrical resistance of a via in a semiconductor device to increase slightly after a process induced thermal cycle such as a film deposition. However, a via in certain types of prior art semiconductor devices can sometimes exhibit a significant increase in via resistance during a subsequent thermal cycle. In some cases the increase in the electrical resistance of a via can range from twenty percent (20%) up to as much as one hundred fifty percent (150%). In addition, a via in some types of prior art semiconductor devices can also sometimes significantly expand in volume after a process induced thermal cycle.
One cause of the observed increase in the electrical resistance of the via and the observed volume expansion of the via is the presence of a fluorine contaminant embedded in a layer of anti-reflective coating (ARC) titanium nitride (TiN) in the semiconductor device. The fluorine contaminant becomes embedded in the ARC TiN layer during an etch process for a via passage that partially etches into the ARC TiN layer. The fluorine chemically reacts with a layer of titanium during subsequent thermal process steps to form a titanium fluoride compound.
The titanium fluoride compound exhibits an increased electrical resistance and an increase in volume. The presence of the titanium fluoride compound increases the electrical resistance of the via. In addition, the presence of the titanium fluoride compound contributes to an undesirable increase in via volume.
Therefore, there is a need in the art for a system and method for minimizing increases in via resistance during the manufacture of a semiconductor device. There is also a need in the art for a system and method for ensuring that a fluorine contaminant will not chemically react to form a titanium fluoride compound in a via of a semiconductor device.